bladder cancer and smokerTwo recent studies illustrate the danger of smoking, especially among diabetics who take insulin.  New research studies conducted in Taiwan and Turkey and reported by Cancer Monthly show that the risk of bladder cancer is exacerbated by smoking. The risk was even higher among diabetics who were on insulin.

Evidence suggests that people with type 2 diabetes face a higher risk of bladder cancer than the general public (“Bladder Cancer and diabetes”, Diapedia,, but certain drugs and other agents can compound the risk. A study published in Clinical Genitourinary Cancer followed the cases of more than 86,000 patients with type 2 diabetes from 1995 to 2006 to evaluate the joint effect of insulin use and smoking.

Patients who died of bladder cancer were typically older men who had had diabetes for many years and who both smoked and used insulin. Author CH Tseng of the Taiwan University College of Medicine reports, “The adjusted hazard ratios for bladder cancer mortality for insulin users vs. nonusers ranged from 1.877 to 2.502…Insulin use and smoking jointly increased the adjusted hazard ratio to 3.120.” Tseng concludes that insulin use is “significantly predictive for bladder cancer mortality” and that, together, insulin use and smoking increase the risk further.

Another study published in the European Journal of Cancer Prevention analyzed the cases of 173 patients with bladder cancer and compared them with 282 control subjects who did not have bladder cancer. The patients had all been admitted to a Turkish hospital in 2011 for a variety of diseases.

For patients who smoked fewer than 20 cigarettes a day, the odds ratio for developing bladder cancer was 2.9. For heavy smokers (more than 20 cigarettes a day), the odds ratio was 4.0. The researchers conclude, “Tobacco is the major risk factor for bladder cancer in Manisa, being responsible for 56% of cases.” The studies highlight the importance of not smoking, especially among people with type 2 diabetes.

The original studies were published in Clinical Genitourinary Cancer (Tseng, CH, “Insulin use and smoking jointly increase the risk of bladder cancer mortality in paitients with type 2 diabetes”, December 2013, Clinical Genitourinary Cancer, pp. 508-514, and the European Journal of Cancer Prevention. (Erdurak, K, et al, “Smoking, occupation, history of selected diseases and bladder cancer risk in Manisa, Turkey”, January 2014, European Journal of Cancer Prevention, pp. 58-61,

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